What is country ...?

I am trying to understand what country music is. What is it that differentiates it from other genres? Today's country does not sound like traditional country. How can an artist just suddenly decide to be country (such as Jewel and Bon Jovi) without really changing their style? The only thing that I have been able to come up with that seems to be consitstent in country is ballads. Do you have anyother ideas?